Children conceived with donated sperm are fighting a law which prevents them from obtaining details about their biological father.

The civil rights organisation Liberty is bringing a test case to challenge the law, which if successful could enable hundreds of people to trace their father.

Liberty is expected to begin its action in October and is challenging the existing law under the government's human rights legislation which comes into effect next month.

The case is being brought on behalf of brother and sister Adam and Jo Rose, along with other adults who claim the existing ban on information breaches their rights to respect for private and family life.

They will argue that non-identifying medical information should automatically be made available to children who were conceived with donor sperm.

We think this is an important issue

Liberty spokeswoman

They will also suggest that an independent third party organisation should be set up to mediate, should a child wish to trace his or her biological parent.

Under this scheme, donors would be contacted and asked whether they wished their details to be passed onto the child.

A spokeswoman for Liberty said the system would be similar to the one used to help children who have been adopted.

She said that it would balance the child's needs with the donor's right to remain anonymous.

She added: "We think this is an important issue and a good example of how the human rights act can be used to test peoples rights."

The Department of Health said in July last year that ministers had ordered an investigation into the social and legal implications of a change in the law on identifying sperm donors.

A spokesman said that ministers were still considering introducing changes to existing legislation.

However, he added that a consultation paper was not imminent.

It is illegal in most countries for donor inseminated children to be told the identity of their parents.